Working in regions affected by active armed conflict poses the challenge of “complex development.” In these settings, often the fabric of communities has been worn down by protracted conflict or the behaviors of some actors—by explicit design or as an unintended consequence—can reverse development gains. The challenges of complex development are central in places like South Sudan, Afghanistan, the FATA in Pakistan, or Somalia. How can they be overcome? In general, what are the key elements of success in promoting development in conflict-affected environments? Finally, why do development investments in conflict-affected countries strengthen U.S. security and, more broadly, the security of the global community?